1. Field of the Invention
The present invention relates to a technology for adjusting a position of a component in a fixing device of an image forming apparatus.
2. Description of the Related Art
As is well known, in image forming apparatuses such as printers, copiers, facsimile apparatuses, or printing machines, an electrostatic latent image formed on an image carrier is developed with toner into a toner image, and the toner image is transferred and fixed onto a recording medium, so that a copy of an original is obtained.
A fixing device is commonly employed that has a heat-roller fixing system in which a pair of rollers is opposed to each other across a path for conveying a recording medium.
The fixing device includes various sensors to control temperature, safety, exchange timing of the fixing device, or the like. The sensors are arranged so that an appropriate positional relation to a fixing member that is used for fixing is maintained.
The sensors formed as electric components are connected to a control unit or the like through a harness. A harness is susceptible to heat unlike a sensor. Therefore, positional accuracy with the fixing member is seriously controlled with respect to a position at which a harness is wired as well as a position of a sensor, as safety measures for disconnecting or the like.
For example, Japanese Patent Application Laid-open No. H11-149229 discloses a conventional configuration concerning arrangement of a sensor. Specifically, a temperature sensor that detects temperature of a surface of a fixing roller as a fixing member is arranged to a free end of a cantilever plate spring so that the temperature sensor comes into contact with the surface of the fixing roller. The position at which the temperature sensor comes into contact with the surface of the fixing roller is adjusted depending on rotation of the fixing roller or stopping of rotation of the fixing roller while the temperature sensor is controlled to keep coming into contact with the surface of the fixing roller by a plate spring. Furthermore, Japanese Patent No. 3808069 discloses another configuration concerning arrangement of a sensor. In this technology, a predetermined space between a fixing roller and a temperature sensor that are opposed to each other is maintained such that the temperature sensor is attached to an arm that is connected to and supported by a frame through a plate spring, and a direction in which the temperature sensor comes into contact with or released from a peripheral surface of the fixing roller is determined based on a fastening force to a plate spring as well as movement of the arm at a position at which it is connected to the frame.
However, a supporting member that supports the temperature sensor needs to have high accuracy in determining a positional relation with the fixing roller. Therefore, processing accuracy and assembling accuracy are required for the supporting member, leading to an increase of manufacturing costs. Particularly, as Japanese Patent Application Laid-open No. H11-149229 discloses, when a position of the temperature sensor with respect to the fixing roller can be adjusted, a space occupied by the supporting member needs to include an extra space where the temperature sensor is to be adjusted. Therefore, a space for the supporting member in a fixing device is increased. As a result, a size of the fixing device increases, increasing manufacturing costs.